Election 2017: 10 things you need to know about the campaign

We've had manifestos, gaffes and a tightening in the polls. But what else have we learned since Theresa May called a snap election?

1) 'Don't make up manifestos on the hoof'

The party manifesto is a key document that has the potential to make or break an election campaign, as Theresa May experienced following the launch of the Conservative's.

Her party's plan to make elderly people requiring care at home liable for the costs - apart from £100,000, which they could keep - proved controversial.

The policy, which would delay people's payment from their estates until after they died, meant some people - and many typical Tory voters - would not be able to pass their home on to their children.

It took Mrs May just four days - and lots of negative reaction - to add that there would be a cap to the amount of money one person would pay for care.

There had been no mention of a limit in the manifesto and ministers had publically rejected the idea. But the prime minister denied claims of a U-turn.

The moral is "don't make up significant manifesto policies on the hoof", John Curtice, professor of politics at Strathclyde University, says.

2) Politicians need to know their facts - and people's names

For any politician who has a live broadcast interview, preparation - and knowledge of your party's policies - is essential.

Two gaffes stand out. Shadow home secretary Diane Abbott mixed-up her numbers in an interview with LBC's Nick Ferrari, while party leader Jeremy Corbyn stumbled over the cost of Labour's plan for free childcare on BBC Radio 4's Woman's Hour, managing only "a lot".

"It was almost a Diane Abbott moment," says BBC assistant political editor Norman Smith. "He was clearly struggling badly for the numbers."

It was names that proved tricky during the ITV leaders' debate for UKIP leader Paul Nuttall.

He called Plaid Cymru's Leanne Wood "Natalie" twice, despite there being no Natalie on the panel.

"The classic moments [of election campaigns] are the ones when things go wrong, because they are so controlled," says Steven Fielding, professor of political history at the University of Nottingham.

3) Two-party politics is back - for most of us

Are coalition governments a thing of the past?

Historically the Conservatives and Labour have commanded the majority share of the vote in general elections, with smaller parties not getting much of a look-in.

Then, in 2010, we had a coalition government with the Conservatives and Liberal Democrats, as neither of the two larger parties could command a majority.

And in 2015, nearly four million people voted for UKIP. This secured only one MP but the party achieved 12.6% of the popular vote, putting it third behind the Conservatives and Labour.

For a while, it looked like the era of two-party politics might be on the decline.

But then UKIP lost 145 councillors in May's local elections in England and Wales. UKIP voters are turning to the Tories now that Brexit is on, BBC political correspondent Ben Wright says.

The Lib Dems don't seem to have made much of a recovery from their 2015 losses, leaving the Tories and Labour the only real contenders.

But Prof Curtice says it's important not to forget about the SNP.

"Two-party politics is only back in England and Wales - not in Scotland, and as a result there will still be a lot of third party MPs in the next parliament," he says.

4) This is the "Theresa May" campaign

The "Theresa May" battle bus

Battle buses are the key staple of any good election campaign, but this year they appear to tell a tale.

The Conservative Party battle bus is all about "Theresa May", while many of the party's campaign signs read "Theresa May's Team".

As the Telegraph's parliamentary sketchwriter, Michael Deacon notes, the Tory campaign has a "downright presidential focus on leader rather than party".

In contrast, Labour's battle bus focuses on the party - rather than their leader Jeremy Corbyn - and some election leaflets are the same.

"Jeremy does not go down well with our core Labour support," says Newcastle-under-Lyme Labour candidate Paul Farrelly, who does not put Mr Corbyn on his leaflets.

In comparison, there is no mention of Jeremy Corbyn on Labour's battle bus

Prof Fielding says it is not unusual for parties to use their leaders in this "all encompassing way".

"In the 1945 election, the Conservatives knew they were not popular - but they also knew that Winston Churchill was incredibly popular, so they actually called their manifesto Mr Churchill's Declaration of Policy," he says.

However it did not work. Mr Churchill lost.

5) There are more women running for office

About 30% of candidates are women - up from the previous record of 26% in 2015, although the actual number of women standing is down from 1,036 to 983.

There are, however, fewer candidates overall standing - about 3,300 compared to 3,971 in 2015.

But about 7.5 million people will not be able to vote for a woman as more than 100 constituencies across the UK have no female candidate on the ballot. according to BBC research.

There is one seat where it is impossible to elect a man to Parliament: Glasgow Central has four names on the ballot - all are women.

6) Labour has done better than expected

When Mrs May called this snap election, the Conservative Party was ahead in the polls by some way.

But Labour has been closing the gap.

However, senior elections and political analyst Peter Barnes warns there are still quite large differences between the pollsters' figures.

And, as we learned in 2015, the polls can be wrong.

Almost all of the pollsters have changed their methods since then, but we won't know how successfully until 8 June.

7) Young people can make a difference

Young people prefer Labour over the Conservatives, according to opinion polls, but the majority don't vote.

If 18-24-year-olds turned out to vote as much as over 65 year olds, that could result in five to 10 seats transferring from Conservative to Labour, according to BBC analysis.

That might not sound like a lot, but in a tight election such as 2015, it could make a big difference.

As the Tories ended up with a majority of only 12 seats, any changes could have led to minority government or another coalition.

8) There were three million extra voters in the EU referendum

The EU referendum saw a huge increase in the number of people turning out to vote.

Broadly speaking, 2.9 million more people voted in the referendum, compared with the May 2015 general election, David Cowling, a political opinion polling specialist from King's College London, says.

The turnout for the referendum was the largest turnout in England since the 1992 general election and largest in Wales since the 1997 general election.

The big question is, will they return this time?

9) Ethnic minorities are under-represented by London candidates

About 50% of London constituencies have no Black, Asian and minority ethnic (BAME) candidates in the five main parties.

Also five of the consistencies with no BAME candidates have a population of more than 50% BAME.

UK hip-hop artist Guvna B told the BBC: "It's really strange for me that there is not enough representation at that level."

10) It isn't all about Brexit

Half of Britain's adults see Brexit as the most important issue in the UK, a poll by Ipsos Mori suggested before the snap election was called.

The Liberal Democrats have centred their campaign on the issue of Brexit, offering a second referendum on a deal, as have the Green Party.

But Prof Stephen Fisher, from Oxford University, says: "Most people who voted Remain are not desperate for a second referendum."

According to a YouGov survey published earlier this month, 23% of people questioned were classed as "Re-Leavers" - those who voted to Remain in the EU but think that the government has a duty to leave, and 45% were "Hard Leavers" who want out.

That left only 22% of people who were "Hard Remainers" - those who want to stop Brexit - and 9% who didn't know.

So it might not be the Brexit election after all.